Doppler optical coherence tomography (D-OCT) techniques enable high resolution (˜10 μm) imaging of microvasculature. (See Z. P. Chen et al., “Optical Doppler tomographic imaging of fluid flow velocity in highly scattering media,” Optics Letters 22, 64-66 (1997); and J. A. Izatt et al., “In vivo bidirectional color Doppler flow imaging of picoliter blood volumes using optical coherence tomograghy,” Optics Letters 22, 1439-1441 (1997)). Because of a possible significance of vascular morphology and function across a broad range of diseases, the potential of D-OCT techniques and uses thereof can extend from applications in diagnostic imaging to basic studies of vascular biology and vascular responses to therapy. The successful adoption of these techniques for such applications can depend in part on how well D-OCT systems are able to comprehensively map vascular networks in three-dimensions. It may be important for this effort to provide the capability of D-OCT systems to image rapidly and with high flow sensitivity.
Current D-OCT systems can predominately utilize a phase-resolved technique, as described in Y. Zhao et al., “Phase-resolved optical coherence tomography and optical Doppler tomography for imaging blood flow in human skin with fast scanning speed and high velocity sensitivity,” Optics Letters 25, 114 (2000), that can be based on the detection of phase shifts between sequential A-lines (e.g., depth scans) that may result from motion within the sample, e.g., blood flow. The phase shift, e.g., v∥, that results from a given scatter translating in the direction of the imaging beam with a velocity, v∥, can be provided as
                    Δϕ        =                              (                                          4                ⁢                π                ⁢                                                                  ⁢                n                            λ                        )                    ·                      v            ||                    ·          T                                    (        1        )            where n is the refractive index of the material, v∥ is the mean wavelength of the OCT imaging system, and T is the Doppler integration window which is equal to the time separation between phase measurements. The acquisition of the exemplary Doppler images may proceed by measuring the phase difference as a function of depth (z) and transverse coordinate (x), Δφ(z,x)). While the majority of exemplary D-OCT systems may utilize a ramp beam-scan pattern that translates the beam at a constant velocity across the field of view (FOV), alternate scan patterns may be used to affect both the Doppler integration window, T, as well as the phase noise background, and improve Doppler imaging performance.
There may be a need to overcome certain deficiencies associated with the conventional arrangements and methods described above.